1000W would make me edgy. The 285's can pull just shy of 200W a piece, before overclocking, and an overclocked i7 can see north of 200W without too much trouble. While the odds of maxing both out simultaneously are slim, that only leaves around 200-250W for everything else, which can disappear pretty quickly. You can find plenty of testimonials from people running that kind of stuff on a 1KW without any trouble, but personally, (were I inclined to build a rig like that for myself), I'd definitely be looking at something stronger than a 1KW PSU.